Hi there
I dont have any experience with Whippets but i do of working my dogs at differing weights .
A dog stripped down shall run/turn alot faster but can only keep it up for short bursts quite simply because they dont have any reserves.
I have quite watched dogs literally work weight off in a hard day out.
If i wanted a dog to work hard over a longer period i wouldnt expect it to do so if stripped .
It is horses for courses ,so to speak lol